NON reloading question PLEASE......

[Don2]

Looking for a CB antenna expert:

Sorry to bother yall with a non reloading question, but I can't seem to find this info anywhere and no one to talk to..!

I'm setting up a CB radio in my reloading shop ( This should cover the reloading topic criteria ) and am building a vertical wire antenna with ground plane wires. Question is, is it ok to earth ground the shield on the coax cable, or does it need to float?

I have an "L" bracket with coax connector that I am wanting to bolt to a metal pole which will be in the ground and 20 or so feet in the air. I just ohm'ed out the shield of the coax and it is grounded to the "L" bracket. So this means it will be going to earth ground too.
I understand the ground plane wires need to be run out from the pole and insulated from anything. This is what is confusing me.
They will be to earth ground through the pole????

Just getting into this...Hope someone can help.

http://www.livecbradio.com/home-made-cb ... ntenna.htm" onclick="window.open(this.href);return false;
This is pretty much what I am building, except the center wire will be connected to a 106" Stainless whip antenna.
Now I have to buy a SWR meter.
I sold all my CB stuff years ago. What little I had. I did keep my Cobra 25 LTD Classic
Thats what I'm using.


Don2

[Gyrogearhead]

Hi Don,

Interesting question about ground plane antennas. I just looked up the subject in my handy "Ham Radio Operator's Guide" and found that the recommended method is to have the ground plane wires insulated from the mast and firmly soldered to the feed line coax shield. The feed line coax is grounded through the chassis of your transmitter or transcever. If you ground the line at the mast you will form a "ground loop" through the earth ground to the power cord ground to your Xcever to the feed line coax and back to the mast. Not a good idea; it can cause serious problems in your final drive circuits.

If you ground the antenna at the mast but not at the Xcever chassis you will cut the effective transmitted power quite a bit. Best thing is to figure out how to insulate the "L" bracket from the mast. This might be easily done by wrapping a bit of tire inner tube around the mast and using stainless hose clamps to fasten the vertical part of the L to the mast. You'll also want to solder a bit of heavy gage wire to the L bracket and bend it so it just barely does not touch the mast. This will act as a lightening arrestor and will go a long way toward saving your final amplifier in case of a ligntening strike, not to mention the inside of your reloading room, powder & etc.

Hope this helps,

Gerry

[Don2]

Egg-Zackley what I was thinking.

I think the long whip antenna bracket was made for a truck where I think you would want the shield connected to the common ground on the chassis..!

My plan was to keep the bracket insulated from the antenna pole/ground anyway, so this just confirms it.

That should work nicely.

My problem now is the coax cable I have ( about 500' ) has a steel braided shield wire which makes it hard to impossible to solder my ground plane wires to or even mount a connector, unless there is a type connector that does not require soldering shield to it????
Just trying to do this antenna job cheaply, I had this cable here in my shop for years...Just wanted to use it up.

Maybe I'm just getting old, but stuff is really going up in price lately. Like a 1000' roll of cable..!!!!
Sheesh..........Good thing I'm in NO hurry.


Don2

[Gyrogearhead]

Hi Don 2,

The ground plane wires do not have to be actually soldered to the "shield" braid of the coax cable as long as the shield makes good electrical connection to the "L" bracket. Just solder or weld the wires to the "L" bracket and insulate it from the support mast like you were planning. I'm asuming here that you have a screw on connector on the end of the cable that screws into the base of the antenna at a connector socket under the "L" bracket. If you have a socket but no screw on connector for the cable, the connectors are only a couple of bucks at Radio Shack or on line at http://www.digikey.com" onclick="window.open(this.href);return false;

The connectors I've used for coax generally don't require soldering the braid to the connector. They have a separate sleeve piece that goes on over the bare braid after you stip off the insulation. Then you fold the braid back over the sleeve and screw the connector onto the sleeve trapping the braid between the metal parts of the connector. At the same time the center wire of the coax sticks out through the hollow center conductor of the connector where you apply a drop of solder to finish the installation. It's quick and quite easy but be aware there are no instructions supplied with the connector usually.

If what i've described is not what you've got then you may have to jury rig something. In that case the main thing to remember is the center wire of the coax cable must not come closer to ground, the antenna mast or the braided shield than the thickness of the insulation inside the cable. The ground plane wires must be in good electrical contact with the shield braid (soldering the ends of the ground plane wires together with a pig tail of wire to wrap around the exposed shield braid will probably work as well as anything if you can't get solder to stick to the braid.)

I forgot to mention in my last post that in my Ham Radio book it says that the ground plane wires should be angled down from horizontal at 45 degrees and that the more there are of them the better the antenna works. Four wires are considered minimum number.

Gerry

P.S. Sometimes coax cables have a small uninsulated copper wire run under the braid if the braid is not copper. This wire is what you use for electrical connection to the braid. If you strip off the rubber outer insulation and push back the braid you may find this wire hidden underneath. If you plan to make up the antenna connection without a screw on connector then use this wire for your ground plane connection.

[Don2]

THANK YOU VERY MUCH...You have been very helpful...!!!!

Back in the day....I guess the braided shield wires use to be copper or copper clad. I just have not used any of the new connectors, but I understand their use.
My coax cable to my satellite tv dish works the same way with the connector as you mentioned.
I have installed a few of them, so I just have to make a trip to RadioShack and look around. Or maybe online??

Ok....At least 4 ground plane wires...I could easily attach as many as I have room for...Maybe eight would be better?
Oh...At a 45 deg angle to the ground...

This is going to be fun....I am collecting all the materials needed now and should be ok except for the connectors for the coax.

I wish I could put a higher pole/antenna, but looks like all I can handle by myself may be about 30'. I do have a tractor with front end loaded I can use to help mount/hold it.
Even at 30', I guess I should use guy-wires...I have the ring that mounts on the mast to attach guy- wires to, so I should use them so I don't have to do it all over when the first Northern blows in..!!!

I am sure glad I can use the big roll of coax cable I have...It was given to me a while back. It is a wooden spool that was 1000' roll with some used off of it.

Next project is an old shortwave receiver I have, its a Hallicrafters S-120 ( Tube type ) I plugged it in a few weeks ago and it seems to work fine...can't pick up much yet, just had a long line hooked up. ( I'm sure it was not done correctly as per my reading, but it did pick up some )

Thanks a bunch...I'm on my way now ..!!


Don2

Ps...This looks like the connectors I need for the coax.
http://www.radioshack.com/product/index ... id=prod_cs#" onclick="window.open(this.href);return false;

[Gyrogearhead]

THANK YOU VERY MUCH...You have been very helpful...!!!!
...
Thanks a bunch...I'm on my way now ..!!


Don2

Ps...This looks like the connectors I need for the coax.
http://www.radioshack.com/product/index ... id=prod_cs#" onclick="window.open(this.href);return false;

Well, Don, You are very welcome. I'm pleased to have been of assistance.

One minor note of caution though is that the plug illustrated in the Radio Shack link comes in various sizes on the wire end to fit the various wire diameters that it will work with. It's not "one size fits all" so look on the outer insulation of your coax and get the right number to match to the plug. (It will probably be a number like: RG-{two numbers}, eg: RG-58, which is about as big as your little finger.) Alternatively take a short piece of your coax with you to R/S and go through their stock til you find one that fits over the braid just right.

Good Luck,

Gerry

[Gyrogearhead]

Don,

For What It's Worth:

I just had another thought, in case you are thinking to use 30' of conduit as an antenna mast.

I saw one like that some years ago rigged up like a sail boat mast with spreader bars at about the mid point and wire guys from the top, over the spreaders to attach to the bottom. In addition there were smaller spreaders at the 1/4 points with guys from the top over the smaller spreaders attached to the mast at the mid point spreaders and then on down over the the lower 1/4 point spreaders and attached at the base.

This makes a double braced mast of relatively small diameter that is incredibly stiff. It can be guyed from the lower 1/4 point to "Earth anchors" you can get at Lowe's and auger into the ground 7-8' away creating a relatively small footprint.

This will keep you from having to have guy wires from the top and middle of the mast all the way out to a rock or tree stump in the South-40 somewhere. Just make sure the base of the mast can't go sideways even a little bit cause it sure will want to do that in any kind of breeze.

Gerry

[Don2]

THANK YOU VERY MUCH...You have been very helpful...!!!!
...
Thanks a bunch...I'm on my way now ..!!


Don2

Ps...This looks like the connectors I need for the coax.
http://www.radioshack.com/product/index ... id=prod_cs#" onclick="window.open(this.href);return false;

Well, Don, You are very welcome. I'm pleased to have been of assistance.

One minor note of caution though is that the plug illustrated in the Radio Shack link comes in various sizes on the wire end to fit the various wire diameters that it will work with. It's not "one size fits all" so look on the outer insulation of your coax and get the right number to match to the plug. (It will probably be a number like: RG-{two numbers}, eg: RG-58, which is about as big as your little finger.) Alternatively take a short piece of your coax with you to R/S and go through their stock til you find one that fits over the braid just right.

Good Luck,

Gerry

The deal with Radio Shack and where I live is, there is a Radio Shack about 30 miles from me that I drive by every week, and I live in a small community in the woods far away from the big cities where there are parts of any kind within a mile or so....I use to live in Houston, born there, then got smart and moved to the woods

I NEVER trust Radio Shack employees or Auto parts either..!!!
I always bring the part with me....LEARNED THE HARD WAY..!!
Mostly just kids reading whatever is on their screen...Not like old auto parts where retired mechanics got jobs that were easier than rebuilding transmissions or engines ..!!! ( They could get your part needed in the dark with no part number )
I was one of thoes kids working at an auto parts many,many years ago with real mechanics that just walked back and grabbed the part the customer needed without looking through all the books..Now they got computers and still get it wrong.

I just converted a 600 watt computer power supply to a DC bench power supply. Works great, but needs some banana plugs from radio shack too...So I have a list of stuff to get from RS .
Righ now I'm messing around and waiting for it to cool down some....Getting all my parts ready to setup. Outside work @100 degs. for me is killer these dayZ.
Thanks a MILLION.
Don